Centrifugal switch



y 1929. c. A. SCHELD GENTRIFUGAL SWITCH Filed 0013. 15, 1927 Inventor. chowles A. schild,

' His Atbo-P'neg.

Patented May 14, 1929.

UNITED STATES 1,713,148 PATENT OFFICE.

CHARLES A. SCHILD, OF FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIO COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL swrrciar.

Application filed October 13, 1927.

My invention relates to switches and more particularly to centrifugally actuated switches.

A centrifugal switch should open or close the circuit in which it is arranged quickly and positively when the rotatable portion of the switch reaches the speed for which it is adjusted to operate. Moreover, it is desirable upon reaching this speed and opening or closing the circuit that the switch should have no tendency to return to its initial position until there is a substantial decrease in its speed of rotation.

Centrifugal switches as heretofore constructed and having these operating characteristics have been complicated, and it is the object of my invention to provide. a simple and improved centrifugal switch which will operate with a snap action and which will have no tendency to return to its initial position until-its speed of rotation has substantially decreased. I do this by employing rotatable weights acting on a spring member of such form that its resistance to the centrifugal force of the weights decreases as it is deflected thereby from its initial position to control the contacts of the switch.

My invention will be more fully set forth in the following description referring to the 0 accompanying drawing and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a longitudinal section of short circuiting device for a commutator embodying my invention showing the device before the commutator is short circuited; Fig. 2 is an end elevation of the device shown in Fig. 1, and Fig. 3 is a view similar to Fig. 1 showing the commutator short circuited.

Referring to the drawing, I have shown my invention, for convenience in illustration, as applied to a short circuiting device forthe commutator 10 of a repulsion induction motor. The commutator is arranged on the shaft 11 of the motor and includes the usual insulated segments 10 the ends of which form contacts 10 adapted to engage a short circuiting device. In accordance with my invention the short circuiting device comprises a spring member 12 having a concave surface 12 (Fig. 1) so that it is adapted to be flexed with a snap action to decrease the con- Serial No. 226,007.

cavity of the surface. Flexing such a concave spring member in this manner takes place with a snap action because the force resisting the change in the concavity of the surface decreases as the concavity of the surface decreases. In order to adapt the concave spring member to the particular short circuiting device shown, it is made annular in form and secured to the shaft 11 between collars 13 and 14. The collars and the spring member are retained on the shaft against a coil spring 15, by a ring 16 seated in a groove 17 in the shaft 11, in such position that the spring member can be flexed from a position out of engagement with the commutator segments 10 into engagement therewith to short circuit the commutator. The inner periphery of the spring member 12 engages the end of the collar 14:, and a flange 13 of the collar 13 engages the spring member radially outward from the shaft so that the coil spring 15 resists flexing of the spring member. A spacing washer 15 is arranged between the spring and the commutator and it can be replaced by a thicker or thinner one to adjust the force of the spring and the speed of rotation of the shaft 11 at which the commutator is short circuited. Any suitable means may be employed for flexing the spring member 12 upon rotation of the commutator, but in this instance I employ a plurality of weights 18 attached to the concave surface of the spring member. By this arrangement, upon rotation of the shaft 11 and the spring member 12 each weight exerts centrifugal force tending to flex the spring member from the position shown in Fig. 1 to that shown in Fig. 3, in which position it is slightly of the opposite concavity to that shown in Fig. 1.

In operation of the centrifugal short circuiting device described, upon starting the motor the spring member 12 is in the config- 10 formed on the segments 10 and short cir- 110 cuitsthe commutator. The resistance of the spring member decreasesinthis manner to produce a snap action because as the spring member is flattened the deformation and peripheral elongationthereof becomes less in proportion to the movement of the outer periphery thereof axially of the shaft. The spring member sliort'circuits the commutator "until there is a considerable decrease in the speed of rotation of the shaft 11 because the change in the configuration of the spring mem er l2 greatly lessens its resistance to the centrifugal force of the weights. It will thus be seen that after the speed of rotation of the shaft 11 becomes great enough to snap the spring member 12 against the commutator that there is no tendency for. the spring member to move away therefrom upon a slight decrease in speed of the shaft 11.

Although I have shown my invention applied to a centrifugal short circuiting device for a commutator, it is apparent that it is applicable as well to a switch of any other form. I desire it to be understood, therefore, that my invention is not limited to the particular arrangement shown and described, and I intend in the appended claims to cover all modifications which do not depart from the spirit I and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. Afcentrifugal switch comprising a rotatable element and contacts, a spring member having a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of said surface, and means actuated by centrifugal force produced by rotation of said element for flexing said spring member and controlling the circuit between said contacts.

2. A centrifugal switch comprising a rotatable element and contacts, an'annular spring member having a concave surface so, that it is adapted to be flexed with a snap action to decrease the concavity of said surface, and means actuated by centrifugal force produced by rotation of said element for flexing said spring member and controlling the circuit be tween said contacts.

3. A centrifugal switch comprising contacts, an annular spring member having a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of said surface, means for supporting said annular member including a rotatable element engaging its inner periphery, and means actuated by centrifugal force produced by rotation of said element for flexing said annular member about its support and controlling the circuit between said contacts.

4. A centrifugal switch comprising a rotatable element and contacts, an annular spring having a concave surface so that it is adapted to, be flexed with a snap action to decrease the concavity of said surface, means for seeluding an annular spring member su curing said annular member L0 said rotatable element, and means actuated by centrifugai force produced by rotation of said element for flexing said annular member about its support and controlling the circuit between said contacts including weights arranged about the periphery of said member.

5. A centrifugal switch comprising a rotatable element and contacts, a spring member having concave surface so that it is adapted to be flexed with a snap action to a configuration in which said concave surface is convex, and means actuated by centrifugal force pro-" duced by rotation of said element for flexing said spring member and controlling the circuit between said contacts.

6. A centrifugal switch comprising a rotatable element and contacts, means for con trolling a circuit between said contacts in* cluding an annular spring member supported at its inner periphery on said rotatable element and having a concave surface so that it is adapted to be flexed with a snap action to a configuration in which said concave surface. is convex, and means actuated by centrifugal force produced'by rotation of said element for flexing said annular member to control the circuit between said contacts including weights secured to said annular member.

7. A centrifugal switch comprising a rotatable element and contacts, means for controlling a circuit between said contacts inorted at its inner periphery on said rotata e element and having a concave surface so that it is adapted to be flexed with a snap action to a configuration in which said concave surface is convex, a spring secured to saidrotatable element and engaging said annular member for maintaining the concavityof said surface ,of said annular member, and means actuated by centrifugal force produced by rotation of said element for flexing said annular member to control the circuit between said contacts including weights secured to said annular member.

8. In'combination with a cummutator, an annular spring member having a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of said surface, means for supporting said annular 1 member adjacent said commutator, and means dependent upon rotation of said commutator forflexing said annular member to bring the same into contact with the segments of said commutator for short circuiting the same.

9. In combination with a commutator, an annular spring memberhaving a concave surface so that it is adapted to be flexed with a snap action to decrease the concavity of said surface, means for supporting said annular member adjacent said commutator, and means dependent upon rotation of said commutator for flexing said annular member to bring the same into contact with the segments of said commutator for short circuiting the same, said flexing means including centrifugal actuated Weights secured to said annular member 10. In combination .With a commutator, an annular spring member having a concave surface so that it is adapted to be flexed With a snap action to decrease the concavity of said surface, means for supporting Said annular member adjacent said commutator, a spring engaging said annular member for mintaining the concavity of said surface of said annular member, and means dependent upon rotation of said commutator for flexing said annular member to bring the same into contact with the segments of said commutator for short circuiting the same, said flexing means comprising eentritugally actuated Weights secured to said annular member,

In Witness whereof, I have hereunto set my hand this 11th day of @ctobe-r, 1927.,

CHARLES A. SCI-1m, I 

